Understanding the different delivery methods for electrical construction can pay off
The delivery method for an electrical construction project can take one of several different forms. Traditionally, the general contractor (GC) hires a designer and a builder. (For the purpose of this article, the GC may be the owner or a construction firm). The designer designs, and the builder builds. This straightforward arrangement works well when there's effective collaboration between the two firms. A breakdown in that teamwork, however, can sometimes lead to adversarial conditions that quickly add costs — materializing in the form of changeorders, extended completion dates, and even litigation. Two other project delivery methods take a different approach, putting all or much of this teamwork under one roof. Striving for lower costs, better quality, and earlier completion dates, these two arrangements are called design-build and design-assist.
Design-build. Instead of implementing the design and specifications provided by another firm, the electrical contractor performs both the design and build functions, working directly with the architect, mechanical/plumbing designers, special systems designers, and the GC. Because the designer and the builder are one in the same, the possibility for adversarial conditions is eliminated.
In the traditional approach, you have what economists call “transaction costs.” Every communication between the designer and the builder costs time and money. Miscommunication results in rework, which costs even more. The design-build approach is attractive to many in the construction industry because it eliminates such transaction costs.
Despite the advantages of this method, however, unfortunately there's no free lunch. The burden that was once on the designer is now placed on the electrical contractor. Consequently, any firm engaging in design-build projects requires expertise that an electrical contractor traditionally does not have.
In this arrangement, the GC relies on the electrical contractor to recommend the latest, most cost-efficient construction methods, and to integrate proven cost-saving techniques into the electrical design. The upside is the electrical contractor, if properly staffed, is in a good position to do those things.
When the GC uses a consulting electrical engineer to provide a schematic level set of design documents and specifications, you have a form of design-build. With these documents produced, the GC can more clearly articulate what the job is when putting it out for bid. Normally, electrical contractors will bid to those very documents.
It's common for the GC to ask each bidding electrical contractor to provide a comprehensive value engineering analysis of the schematic level documents developed by the consulting electrical engineer. The implementation of value engineering practices continues through the design and construction process.
During the design process (from the schematic design level to the construction document phase), the consulting electrical engineer can provide peer review services, but the electrical contractor is the engineer of record.
Design-assist. When a GC obtains the services of an electrical contractor early in the design process to provide extensive value engineering and field detailing services, you have design-assist. In this scenario, the electrical consultant remains the engineer of record.
When in this design-assist role, a qualified electrical contractor will evaluate value-engineering ideas, and the in-house engineering group will review the design to ensure it adheres to good design practice, applicable codes, and any special requirements. The in-house engineering group would also ensure all load calculations are correct, prior to final review by the consulting electrical engineer. This process allows for a smother communication of design alternatives and gives the owner the benefit of multiple engineering viewpoints.
Reaping the benefits. According to the Design Build Institute of America, Washington, D.C., the private sector's use of design-build has been increasing in frequency and application during the past 30 years. In fact, its use has become increasingly common in the United States on projects ranging from commercial and institutional applications to industrial and power projects.
Why have these delivery methods become more popular in the construction industry over the last several decades? For starters, increased collaboration by fewer parties enables contractors to lay their design cards on the table much earlier in the process, reducing the chance for error later. Another advantage that appeals to owners and contractors alike relates to the synergy formed when scope of work, schedules, and design documents are clearly defined from the beginning.
Scope of work. No matter which design collaboration method is selected, the electrical design team must listen closely to the customer and other design participants to gain a clear understanding of the priority of the design parameters. The team must be proactive in suggesting and/or supporting any design options or alternatives that are in the best interest of the project. Once these things are agreed upon, the next step is to define the scope of work. This includes answering such questions as:
What is the square footage of the required build out?
How many floors does the build out require?
Where are the electrical equipment spaces?
Will the electrical distribution system need to accommodate future expansion?
Will the system require a standby generator and/or UPS?
Will the system be required to feed an increased density of power (watts/square foot)?
What are the short-term goals of the project?
What are the long-term goals of the project?
Does the project have any special functional needs?
Schedule and sequence. Schedules should result from collaborative decisions with a clear appreciation for the advantages, costs, and risks associated with schedule choices. Consider these two factors when deciding on the optimal schedule choices:
Critical path design schedule (CPDS) — Work with the design team to set up a real CPDS to get everyone working in a logical order with a minimum of wasted design time. Identify opportunities for early construction starts on critical path construction tasks. Work with the GC to get progressive and timely design review — this facilitates timely equipment ordering and submittal approvals.
Drawings for schedule enhancement — Organize drawings and layering to assist field detailers and installers. Make progressive drawing releases such as below-grade rough-in and box and raceway rough-in. Detail the important field coordination efforts, but minimize details that normally get redone as part of vendor shop drawings.
Design document package. This is a key package of documents used to communicate with the GC, contract administrators, operations staff, construction staff, estimators, schedulers, and others on the team of contractors and designers. It is the baseline from which the contract evolves and performance is measured. At a minimum, the package should include:
Narrative — Provide a short technical description of the scope of the project.
Preliminary one-line drawings — Identify all of the major pieces of electrical distribution equipment, plus the sizing of all major feeders. These drawings also provide basic watts/SF calculations that correlate with the design narrative.
Outline specification — Identify all major systems and equipment, and the means and method for construction (see Sidebar below).
In summary. Is one of these methods superior to the other? The answer depends on how well each party addresses the responsibilities it signs on for. If you're the electrical contractor, carefully assess your existing expertise, and think about how to fill the gaps.
Lane is a registered professional engineer, RCDD/NTS specialist, TPM, LC, LEED A.P. and serves as director/vice president — engineering for SASCO Design/Build Electrical Contractors and Consultants in Woodinville, Wash.
Sidebar: Early Design Decisions
To streamline construction, it helps for electrical contractors to address options for the major systems and equipment early on in the project. These might include:
- Conductors and raceway type: Aluminum, copper, EMT, RGS, MC cable?
- Type of terminations: Mechanical or compression lugs?
- Grounding and bonding: Supplement NEC minimum?
- Transformer windings: Copper or aluminum?
- Transformer ratings: Temperature rating, K-rating?
- Bussing type: Copper or aluminum?
- Breaker type. Thermal, magnetic, or electronic.
- Minimum fault current ratings: For each feeder breaker.
- Breaker ratings. Fully rated and series-rated.
Also address space planning, maintenance and operation, and special issues, such as:
Electrical space matrix: What spaces are required; where they should be?
Specialty issues identification: Anything non-standard may incur long lead times.
Description of maintenance and operational needs: What does the operations staff need and want?
Special acoustical requirements: Barriers, insulation, doors, or special surfaces.
Sustainability requirements: Will the project be LEED certified?
Energy rebates: Whose responsibility it is to apply for available energy rebates?
Startup and commissioning: Identify the most appropriate levels of startup and commissioning for the building occupancy type and construction budget.
Sidebar: The Benefits of Prefab
Many tasks can be more efficiently performed in the shop than on the jobsite. Prefabrication reduces headcount in the field, which can reduce trade conflicts and risk for the entire team.
Using design-build or design-assist, the qualified electrical contractor can evaluate the design to identify opportunities for off-site prefabrication and packaging. This is also true for the traditional approach, but harder to implement.
Prefabrication and packaging can reduce jobsite packaging waste and storage requirements, which often results in significant cost savings. But perhaps even more valuable is the fact that these methods often lead to recommendations of a sequence of work that reduce trade conflicts and rework.